Between 3 and 42% of patients do not initiate their treatments. Non-initiation and non-adherence are associated with poorer clinical outcomes, more days of sick leave and higher costs. The aim of this research project is to generate an effective, efficient and feasible intervention that improve initiation and adherence and improves clinical symptoms. The long-term benefits in terms of improved health and reduced costs will be evaluated. The results will be disseminated to stakeholders, decision-makers and the scientific community to promote implementation. The intervention is expected to improve the clinical practice, empowering the patient. The project develops an innovative approach to the design and evaluation of behavioural interventions that uses the principles of complex interventions, pragmatic trials and implementation research. Nine interventions to reduce non-initiation have been tested. The interventions were not theory-based and most used simple reminders. The evidence supporting these interventions was low and their impact on clinical symptoms and cost-effectiveness was not assessed. The strengths of the IMA-cRCT study are: 1) the main stakeholders are involved in the design and assessment; 2) IMA intervention is theory-based and has been optimized; 3) the study will assess the impact of the intervention on clinical parameters and cost-effectiveness, which is key to guarantee its transferability; 4) the project involves decision-makers; 5) the pragmatic design increases generalisation and 6) the intervention is easily transferable to other pathologies, populations and countries. As part of the ERC research project, a pragmatic cluster randomized controlled trial (cRCT) will evaluate the short-term effects of the IMA intervention and its cost-effectiveness and Markov models will be constructed to estimate its long-term cost-effectiveness. The results will be disseminated to facilitate its transferability to clinical practice in Spain and Europe.